This patent relates to a railway coupler having a shank with a keyslot therein and a draft key projecting through the keyslot.
Although "E" couplers are not constructed to angle vertically, they do angle vertically under buff or draft loading when negotiating vertical curves. In coupler arrangements currently in use, the striker clearance over the coupler shank of a standard coupler allows more vertical angle than can be accommodated by the clearance of the draft key in the coupler keyslot and in the car center sill keyslot. This clearance can become even greater as a result of wear before it would become necessary to make repairs by adding a shim beneath the top wall of the striker opening.
It is for the above reasons that any upward force applied at the coupler pulling face may induce such adverse conditions as bent draft keys, draft keys exhibiting excessive local wear or even coupler shanks being split at the forward portion of the keyslot. In addition, excessive wear can occur on the top and bottom of the striker keyslot due to buff or draft motion while the coupler is angled vertically.
Many of the aforementioned problems in extreme cases can have serious results; for example, a severely bent draft key would be more susceptible to failure under draft loads and can restrict lateral motion of the coupler.